As an ultrasonic transmission/reception unit used in a conventional ultrasonic flow meter device, there is known an ultrasonic transducer or an ultrasonic sensor in which a piezoelectric element is expanded and contracted to generate an ultrasonic pulse. In the ultrasonic transducer, for example, an acoustic matching layer is fastened to an outer wall surface of a case, and a piezoelectric substrate is fastened to an inner wall surface of the case. An opening of the case is closed by a sealing member, and a vibration suppression (damping) member covers a side wall portion of the case. An end portion (support portion) of the case is mounted via a vibration transmission suppression member (prior art example 1: e.g., see Patent Literature 1).
In the ultrasonic sensor, for example, a piezoelectric element is fastened to an acoustic matching layer, and a plastic case is fastened to the acoustic matching layer such that the case covers the piezoelectric element with a gap. An elastic resin such as a silicon resin is filled inside of the case to fill around the piezoelectric element (prior art example 2: e.g., see Patent Literature 2).
Patent Literature 1: Japanese-Laid Open Patent Application Publication No. 2001-159551
Patent Literature 2: Japanese-Laid Open Patent Application Publication No. Hei. 10-224895